Automatic telephone system



Aug. 25, 1.925.-

W. T. POVJELL AUTOMATIC TELEPHONE SYSTEM Filed May 8, 19;?)

WWOIFUMZ ZOU INVENTOR WINFRED T POWELTL.

BY ,&

ATTORNE Patented Aug. 25, 1925.

UNITED STATES! PATENT i-oration.

WINFRED 'r. rowELnoE ROCHESTER, NEW Yonnnssmnon TO (THE STROMBEE,GGARLSON TELEPHONE MANUFACTURING COMPANY, 0E noonns'i nn, NEW roan, A.

CORPORATION 033 NEW YORK.

AU'IQMATIC TELEPHONE SYSTEM.

Application filed May 3,

To all whom it may concern:

,Be itknown that I, \Vmrnnn T. Pow LL, a citizen of the United States,residing in Rochester, in the county of Monroe and State of New York,have invented certain new and useful Improvements inAutomatic,"lelephoneSystems, of which the ;fol lowing is a full, clear, concise,and exact description.

This invention relates to telephone systems, and more particularly tothat class of telephone systems which employs automatic switches incompleting a connection between a calling anda called party.

The present, invention has for its purpose the design of improved andsimplified cir cuits for operating a distributor switclrand for theCQ'OPBI'ZLtlOH of this switch with other automatic switches. Otherfeatures not specifically enumerated will appear from the detaileddescription and from the appended claims.

The drawings diagrammatically represent a portion of the telephonesystem; only so much of this system is shown as is necessary for, acomplete understanding of the present invention. At the lett of thedrawing there is represented a calling substation, while within thed-otted rectangle there is represented the operating circuits of a lineswitch or distributor switch. At the rightof the dotted rectangle nearthe center; of the drawing the operating circuits of a connector switchare shown, while at the extreme right of the drawing a calledsub-station is represented.

.The'linc orldistributor switch which will be reterred'to in thedetailed description, comprises -a flat rotary switch in -which thereare live series of contacts arranged to form an arcuate bank. Fivebrushes are provided; each one of these brushes cooperating with one ofthe five series of contacts. These brushes are rotated only in onedirection; that is, the brushes of the switchare advanced to selectanidle trunk leading to a selector or connector switch and when theconnection is d-ises-tablished the brushes continue to rotate in thesame directionuntil the normal position of the switch is reached.

The connector switch which will be referred to inthe.description,.may;be oiithe type sul'astanti'a-lly the same as thatshown 1919. ,ScriaLNo. 295,7d2.

in the patent to Keith et al. 815,176,,issuedi March 13,1906.

ltis believedithat the operation of this system will'sbestobeUDClQlShOOCLby v:descriloing the method of completing apcall from,

ers line, upper armature. andqback contact of the cut-oifrelayC0,.through the,resist anceil ,to ground.

It should be noted that the linearelay is of the differential type, thatis ,,it is',d.e signed to attract its armature when either of itswindings are energized, but name-.1-

diately-retracts its arn iatures whenboth of its windings aresimultaneously-energized.

Since the opposing'right hand winding of thelinel relay LRisnotenergized at this time, whilethe left hand windingis operated, thisrelay attracts. its, armatureto complete a circuit from ground throughthe,

lower back contact, and armature of the cut-- off relay CO, through ,theback contact,

armature and winding ofthe stepping or motor magnet MM, togroundedbattery.

Underthe control of this circuit, the motor magnet advances the fivebrushesrof the switch from their normal position.

It will be understood that as soon as the brushes have beenHI'OVBCliflOlil normal position, that is, whenbrush5-encounters one ofthe, contacts 10 whiclrare connectedto groundafter the manner of an offnormal, switch, the right hand windlng of the drftest brusl1-6,,tln'oughthe testterininals 1-1 of busytrunks to ground at the armatures andfront contacts of line relays associated with line switches that haveseized these trunks; Then, however, an idle trunk found, the cutoffrelayCO, isencrgized in relay at its left hand contact and armatureseries with the motor magnet MM, through brush 4, through terminal 9,normally closed contact 13, to ground. The motor magnet MM, however,will not operate in series with the cut-off relay. As soon as the cutoffrelay G0. has operated to interrupt the circuit including the left handwinding of the line relay LR, the circuit including the right handwinding of this last named relay is effective to cause the attraction ofits armature to apply a guarding potential to the selected trunk.

As soon as the idle trunk is seized, the stepping relay 'SR of theselector or connector, as the case may be, is energized over a circuittraceable from grounded battery,

winding of this relay, terminal 8, brush 3,

inner front contact and armature of the cutoff relay, through thecalling subscribers sub-station circuit, upper armature and frontcontact of the cut-off relay, brush 2, terminal 7 of the selected trunk,winding of impedance coil 14, to ground. The stepping relay SR attractsits armature and at its front contact completes an energizing circuitfor the slow releasing relay15. This completes a holding circuit for thecutoff relay CO. V

' The subscriber at A now operates his dial switch in accordance with tle first digit of the desired number and since it has been deemednecessary to show only a connector switch, this first digit will be ofthe tens order. In response to the interruptions in circuit of thestepping relay corresponding to the tens digit of the wanted number, thearmature of the stepping relay SR will be caused to vibrate and at itsback contact, completes a circuit for the primary stepping magnet PMfrom grounded battery, through the winding of the magnet, side switchwiper 16 in its first position, wind-- ing of the second slow releasingrelay 17, right hand front contact and armature of relay 15, backcontact and armature of stepping relay SR to ground.

In response to each interruption of the line circuit, the primary magnetattracts its armature and advances its wipers one step in the primarydirection. VVllen the ener' gizing circuit of the primary magnet PM wasfirst completed, the relay 17 was energized and since this relay is slowto releaseit does not retract its armature during momentary inter"uptions of its energizing circuit. As soon as the relay 17 isenergized, a circuit for the escape magnet ESC is closed and maintained,from grounded battery, resistance, winding of the escape magnet,conductor 18, make-before-break contact spring and armature of the relay17 to ground.

the energizing circuit of the stepping relay SR will be maintainedenergized for a relatively long interval, so that the series circuit ofthe primary stepping magnet PM and the slow releasing magnet 17 is heldopen at the back contact and armature of the stepping relay SE. The slowreleasing relay 17 under these conditions, deenergizes and therebyinterrupts the energizing circuit of the escape magnet. This escapemagnet, as is well known, operates on dccnergization to move the sideswitch wipers into their second position. The circuits of the connectorare now in condition to receive the units series of impulses. Inresponse to this series of impulses, the stepping relay SR againvibrates its armature, but in this instance controls the secondarystepping magnet SM- over a circuit completed from grounded battery,winding of the magnet SM, lower armature and back contact of the testrelay 19, side switch wiper 16 in its second position, winding of theslow releasing relay 17, right hand front contact and armature of relay15, back contact and armature of relay SR- to ground.

As soon as the relay 17 attracted its armature in response to the firstof the units series of impulses, theescape magnet ESC is again energizedover a circuit completed from grounded battery, resistance, winding ofthe escape magnet ESQ, conductor 18, makebefore-break contact spring andarmature of relay 17 to ground.

When the slow releasing relay 17 deenergizes at the close of the unitsseries of impulses, the energizing circuit of the escape magnet ESC isinterrupted, if the desired line is idle, and the side switch wipers arethen moved into their third position.

In thisposition or" the side switch wipers ringing current istransmitted to the called sub-station over a circuit traceable fromgrounded battery, through the resistance, ringing machine 23, ringinginterrupter 45, the lamp 2%, winding of the slow releasing relay 25,side switch wiper 26, brush 27, through the called subscriberscircuitincluding the call bell, brush 28, side switch wiper 29 in itsthird position, to ground. The slow releasing relay 25, which iscommonly known as the ringing trip relay, is marginal and does notoperate until the receiver at the called sub-station is removed from itsswitchhook, whereupon it receives suliicient current to operate.

As soon as the side switch moved into its third position, the escapemagnet ESC was energized over a circuit extended from grounded battery,through the resistance, winding of this magnet, side switch wiper 30 inits third position, back contact and armature of release magnet REL, toground.

The escape magnet is held energized in this At the close of the tensseries of impulses,

circuit until the ringing trip relay 25 is energized on the calledpartys response. At

that time the escape magnet is short circnited at-thefront contact andarmature of the relay 25, causing theesca-pe magnet to deenergize andmove its side switch wipers into their fourth, .or talking position.

The subestations .A and YB arenow in telephonic connection, the talkingbattery for the calling sub-station being supplied through thewinding ofstepping relay SR and impedance coil 141-, andthetalkin-g current forthe called subscriber is supplied through the windings of the impedancecoil 31.

It was assumed in the foregoing description that the called sub-stationwas unengaged. If at the timewhen the connector switch had moved itsbrushes 22, 27 and 28 into engagement with the terminals of the calledlinethis linewas busy, abusy tone would have been applied to the callingline and the connection would have failed of completion. It will beremembered that during the units series of impulses, the escape magnetESC was energized over a circuit closed from grounded battery, throughthe resist ance, winding of this magnet, conductor 18, spring contact ofthe relay 17, to ground. At the close of this series of impulses whenthe relay 17 retracts its armature, a. substitute circuit for the escapemagnet is completed which now extends from conductor 18,

spring and contact 20, winding of test relay 19, spring and contact ofthis relay, side switch wiper 21 in itssecondposit-ion, test brush 22,through the terminals of the busy line to ground at side switch wiper 21in their third or fourth positions ,at: busy connect-ors. The test relay19 is energized in this circuit and attracts its armature-s, and at itsupper armature closes a locking circuit for itself to ground at contact32, and off normal spring. At the uppermost armature of the test relay1.9, a circuit is completed for applying a busytone to the callin'g linefrom the busy machine indicated atBZ.

At the close of theconversation when the callling subscriberreplaces hisreceiver on its switchhook, the stepping relay SR which :has'beenmaintained energized during the conversation, retracts its armaturetoo-lose an energizing circuit for the release magnet REL, from groundedbattery, winding of this. magnet, spring and off normal contact 33,right hand back contacts and armatures of relays 15 and SE, to ground.The re lease magnet is energized and operates in the well known mannerto restore the connector switch to its normal position. It will be seenthat as soon as the relay 15 deenergizes, that the holding circuit ofthe cutofl. relay CO is broken at the left hand front contact andarmature of the relay 15. As soon as the cut-off relay deenergizes, themotor magnet MM is operated over a circuit extending frOlIl groundedbatter" ,winding, arm atnre and back contact of the motor magnet MM,lowerarmature and back contact of the cut-,oifrelay, front contact andarmature of line relay-LR, to. grounded battery. The line switchcontinues to advance its brushes in the same direction in which it movedto select. an idle trunk untilthe brush 5 engages the normal contact 13,whereupon the line. relay LR retracts its armature to interrupt theoperating circuit of the motor magnet. in condition to receive anothercall.

In the present disclosure the circuits of the invention have been shownassociated with a line switch which operates to select idle trunksleading to connector switches, but it will be understood that. thesecircuitsmay be employed with any distributor switch,

and if utilized as a line switch, maybe. em-.

ployed to select idle trunks leading toxselec tor switches instead of toconnector switches as herein disclosech. It will be readily understoodthat the distributor circuits here disclosed may be employed toapportion calls .1

to operators on a call distributing system. lVhat I claim is: 1. In atelephone system, ,anincioming line, a. plurality of. out-going lines, adifferential line relay individual to each incomingline.

and controlled in part thereover, a-"cutofi relay individual to eachincoming line, a switch for connecting said incoming line to anyoutgoing line, an operating.magnetior said switch, and a circuit forsaidimagnet The apparatus is now jointly controlled by said lineandcut-oii relays.

2. In a telephone system, an incom ng l ne,

outgoing lines, a switch for interconnecting said incoming line with anyof said outgoing lines, said switch having a normal position,controlling means for said switch including a line relay initiallyenergized over said incoming line, n'ieans for 'deenergizing said linerelay as soon as theswitch ismoved from its normal position, a cut-citrelay operative when-an outgoing line is seized, a magnet for advancingsaid switch, and a circuit for said magnet jointly controlled by saidline and cut-oft relays.

Inan automatic telephone system, an incoming circuit, a plurality ofoutgoing circuits, a switch for interconnecting said incoming circuitwith any of said outgoing circuits,a cut-off relay'individual to saidincoming circuit, a line relay having contacts cooperating in thecontrol of said switch, a circuit for said line relay normally connectsing it to said incoming circuitthrough con.- tacts of said cut-.oiii'relay, means for energizing said line relay and said cut-cit relay whensaid switch seizes an outgoing circuit, and a busy potential for saidselected outgoing circuit applied at contacts of said line relay.

Jil

' 4. In a telephone system, an incoming line,

a plurality of outgoing lines, a normaling non-numerical switch forinterconnecting said incoming line with any of said outgoing lines, aline relay cooperating in the control of said switch, means-to energizesaid line relay, means responsive to the energization interconnectingsaid incoming line with any,

of said outgoing lines, a line relay cooperating in the control of saidswitch, and means controlling said line relay for energizing the same toinitiate the operation of said switch, for deenergizing the same duringthe outgoing line selection operation of said switch and for energizingthe same again during the holding of said outgoing line and during therelease movement of said switch.

6. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines, a line relay and a cut-oil relay cooperating in thecontrol of said switch, means for energizing said line relay to initiatethe line selectin operation of said switch, for deenergizing said linerelay during the line selecting operation of the switch, means foroperating said cutoff relay when an outgoing line is seized, and meansincluding a portion of said first mentioned means and controlled in partby said cut-off relay for energizing said. line relay to effect therelease of said switch.

7. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any 01 saidoutgoing lines, a line relayand a cut-off relay individual to each line,a motor magnet for advancing said switch, said line relay havingwindings diilerentially arranged, a circuit for one winding of said linerelay completed over said incoming line, a cir cuit for the otherwinding of said linerelay completed as soon as said switch is advanced,operating circuits for said motor magnet controlled in part by said lineand cut-oft relays, and a circuit for said cut-ofi relay in shunt oi theoperating circuits of said motormagnet completed while busy trunks arebeing tested.

8. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any 01 saidoutgoing lines, a. motor magnet for advancing said switch, a line relaycooperating in the control of said motor magnet, said line relay havingtwo windings, a circuit completed through one of the windings of saidline relay to cause said motor magnet to advance said switch, means tocause said motor magnet to continue the advance of said switch, and acircuit completed through the other winding of said line relay untilsaid switch is in its normal position for caus- .ing said motor magnetto restore said switch to normal, position. i

9. In a telephonesystem, a plurality of points, means for making pointsunselectable, a non-numerical point finder, a relay having one windingfor initiating the movement of said point finder, means for continuingthe movement of said point finder, a second'winding on said relay forcausing an additional movement of said point finder, means for stoppingthe point finder in engagement with a selectable point, means includinga circuit through one winding of said relay to energize the same andmeans to complete a circuit through another winding of said relay todeenergize the same.

10. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines, an oil-normal contact on said switch, a difi'erentialline relay individual to eaclrincoming line and cooperating in thecontrol of said switch, said relay having two windings, one winding ofsaid relay being energized over the incoming line to start said switch,a circuit for the other winding of said relay completed through saidoil-normal contacts, means for advancing the said switch, and a circuitfor said means controlled in part at said line relay.

11. In a telephone system, an incoming telephone line, aplurality ofoutgoing trunks, means for characterizing said trunks by a busy or idlecondition, av switch for interconnecting said incoming telephone linewith any idle trunk, a dillerential line relay arranged to be energizedover two sides of the talking conductors of said telephone line inseries, means for deenergizing said line relay while busy trunks arebeing en countered and for energizing said line relay when an idle trunkis seized, means for advancing said switch, and an operating circuit forsaid means completed by said line relay.

In witness whereof, I hereunto subscribe my name this 7th day of May A.D. 1919. VVINFRED T. POWELL.

